RA week 10 Flashcards
1
Q
Anterior compartment of the forearm function?
Common flexor origin?
Innervation?
Why?
A
flexion of wrist + digits, and pronation
common flexor origin = medial epicondyle of the humerus
Innervation = median nerve except flexor capri ulnaris + ring/little finger side of flexor digitorum profundus (ulnar nerve)
(Flexor carpi ulnaris lies above the ulnar nerve in the forearm)
(The medial side of flexor digitorum profunduslies directly below the ulnar nerve. It makes sense then, that the ulnar nerve supplies these muscles)
2
Q
Most superficial muscle in anterior compartment?
attachments?
function?
variability?
Innervation?
A
palmaris longus
attaches from medial epicondyle to palmar fascia (aponeurosis)
function = tightens aponeurosis (thought to help grip) + aids with wrist flexion
not present in everyone
innervation = median nerve (C7, 8)
3
Q
pronator teres attachments?
function?
Innervation?
structure?
A
attaches to from medial epicondyle of humerus and coronoid process of ulna to lateral surface of radius
function = pronation (assists elbow flexion)
innervation = median nerve (C6, 7)
. Pronator teres has two heads – the median nerve passes between them
4
Q
would damage to musculocutaneous nerve result in complete absence of elbow flexion?
A
No
As pronator teres crosses the anterior surface of the elbow joint it can also assist in flexion of the elbow, this is a relatively weak movement compared to brachialis but the two muscles are innervated by different nerves (median + musculocutaneous) so some weak elbow flexion would still be possible following damage to the musculocutaneous nerve.
5
Q
flexor carpi unlaris + radialis attachments?
Function?
Innervation?
A
both from medial epicondyle + both flex the wrist
Ulnaris = base pisiform, hamate, 5th metacarpal
- function = adduction of wrist (along with extensor carpi ulnaris)
- innervation = ulnar nerve (C7, 8)
radialis = base of 2nd metacarpal
- function = abduction of wrist (along with extensor carpi radialis)
- median nerve (C6, 7)
6
Q
flexor digitorum superficialis attachments?
function?
innervation?
A
from medial epicondyle of humerus and coronoid process of ulna to → middle phalanges of digits 2-5 (i.e. all except thumb)
(tendon of FDS splits as it passes along each finger)
Function = flexion of wrist + MCP and PIP joint - NOT DIP
innervation = median nerve (C7, C8, T1)
7
Q
flexor digitorum profundus attachments?
Function?
Innervation?
A
part of deeper muscles of forearm
at this level there is no space left on medial epicondyle so originated from ulna + interosseous membrane to → distal phalanges of digits 2-5 (palmar)
function = wrist flexion, flexion of MCP, PIP and DIP of digits 2-5
Innervation:
- Ring and little fingers = ulnar nerve (C8, T1)
- Index and middle fingers = median nerve (C8, T1 anterior interosseous)
8
Q
Flexor pollicis longus attachments?
Function?
Innervatio?
A
Radius and interosseous membrane to → base of distal phalanx of thumb (palmar)
Function = flexion wrist and MCP + IP of thumb (thumb only has 2 phalanges)
Innervation = median nerve (C8, T1 anterior interosseous)
9
Q
Pronator quadratus attachments?
Function?
Innervation?
A
distal anterior ulna to → distal anterior radius
Function = pronation and helps stabilise distal radioulnar joint
Innervation = median nerve (C8, T1, anterior interosseous)
10
Q
Damage to anterior interosseous branch?
A
Pronation by pronator quadratus will be affected
BUT if only anterior interosseous branch of median nerve then pronator teres will still function
11
Q
what is the main nerve of the anterior compartment of the forearm?
formed from?
pathway?
Function?
A
Median nerve
Forms from C6-T1 fibres, medial + lateral cords of the brachial plexus
descends through arm to pass through cubital fossa
passes through anterior compartment of forearm where it forms an anterior interosseous branch before passes through carpal tunnel into palmar surface of hand
Function = main nerve to thumb side of hand (lateral)
supplies sensory innervation to lateral palm, motor to muscles in thenar eminence and to the 2 lateral lumbrical muscles
12
Q
what passes between the heads of pronator teres?
what does it form?
A
median nerve
forms an anterior interosseous branch that runs along the interosseous membrane to supply the deeper muscles of the anterior compartment
13
Q
Ulnar nerve formed from?
Where does ulnar nerve and artery pass?
where does ulnar artery branch from? significance?
Function of ulnar nerve?
A
Ulnar nerve formed from medial cord of brachial plexus (C7?-T1)
From medial epicondyle of humerus to pisiform ABOVE carpal tunnel (does not pass through carpal tunnel)
Ulnar artery forms in cubital fossa as a terminal branch of brachial artery, runs alongside ulnar nerve - it is the major contributor to the superficial palmar arch of the hand
Ulnar nerve supplies flexor carpi ulnaris, medial side of FDP, intrinsic muscles of the hand, sensory to ring + little fingers
14
Q
Ulnar artery branches?
Function?
Where do veins of anterior compartment of forearm drain?
A
Ulnar artery forms a common interosseous artery in the anterior forearm → this divides to form anterior and posterior interosseous arteries that lie either side of the interosseous membrane in the forearm
These vessels supply muscles of both the anterior and posterior compartments of the forearm.
The anterior compartment of the forearm also contains veins that run with the arteries, they eventually drain into brachial veins in the arm
15
Q
Wrist joint?
Type? Movements?
Bones? Features?
Carpal bone joint type?
A
The wrist joint is an articulation between the radius, ulna and carpal bones.
It is a synovial condyloid joint that permits flexion, extension, abduction, adduction and circumduction. The wrist does not rotate – this movement is created by pronation and supination of the forearm
- Some Lovers Try Positions, That They Cannot Handle
Hamate = hook-shaped protuberance that acts as attachment for flexor retinaculum
Capitate = “keystone” that forced generated by movement pass through
Lunate = half-moon shaped when viewed from lateral side
The carpal bones have synovial plane joints between them allowing the carpals to move slightly to accommodate movements of the hand, but stay together to prevent damage to the structures that pass through the carpal tunnel
16
Q
Ligaments associated with the wrist joint?
Roof of carpal tunnel?
A
Medial and lateral colateral ligaments
Many small ligaments between the carpal bones
Thickened part of flexor retinaculum = roof of carpal tunnel
(photograph shows some of the small intercarpal ligaments)
17
Q
Majority of wrist joint?
What is ulnar side associated with?
A
The majority of the articulation at the wrist is between the base of the radius and the proximal row of carpal bones. The distal end of the ulna is much smaller than the distal end of the radius so is associated with an articular disc to increase the congruency of the joint on the medial side
18
Q
Flexor retinaculum function?
Attachments?
Other function?
A
Forms bands on the anterior + posterior surfaces of the wrist - creates roof of carpal tunnel
attachments:
- medial = pisiform + hook of hamate
- lateral = tubercle of scaphoid and ridge on trapezium
- A piece of the retinaculum also passes towards the trapezium bone and creates a small space that the tendon of flexor carpi radialis passes through
The flexor retinaculum also acts as a site of attachment for the small intrinsic muscles of the hand found in the thenar and hypothenar eminences
19
Q
Which structures pass through the carpal tunnel?
So increased pressure in the tunnel?
where do these structures pass?
A
Structures that pass though the carpal tunnel = the tendons of flexor digitorum superficialis, the tendons of flexor digitorum profundus, the tendon of flexor pollicis longus, tendon of flexor carpi radialis and the median nerve
This means that an increase of pressure in the carpal tunnel (carpal tunnel syndrome) can compress the median nerve but will not affect blood supply to the hand. As the diagram shows, the radial artery, radial nerve, ulnar artery and ulnar nerve do not pass through the tunnel.
The ulnar nerve + artery pass over the carpal tunnel to reach the palmar surface of the hand
The radial nerve supplies the posterior compartment of the forearm and ends as a superficial sensory branch that passes over the roof of the anatomical snuffbox and into the hand
The radial artery passes along the lateral side of the anterior compartment of the forearm and through the floor of the anatomical snuffbox before entering the hand
20
Q
Anconeus attachments?
function?
Innervation?
A
attachments = lateral epicondyle of humerus to olecranon of ulna
function = extension of the elbow
innervation = radial nerve (C7-C8/T1)
21
Q
brachioradialis attachments?
function?
innervation?
what is important to note?
A
attachments (found on lateral side of forearm) = distal humerus (supra-epicondylar ridge) to radius proximal to styloid process
function = flexion of elbow, especially when forearm in semi-prone position
Innervation = radial nerve
. It is innervated by the radial nerve but is not an extensor – it crosses the anterior surface of the elbow and acts to flex the elbow joint. So technically classed as posterior forearm?
22
Q
posterior compartment of arm origin?
function?
Innervation?
A
common extensor origin = lateral epicondyle of the humerus
function = extensors of digits + wrist, abductor of thumb, supination
innervation radial nerve
23
Q
extensor carpi radialis longus attachments?
Function?
innervation?
Brevis?
A
longus = distal humerus (supra-epicondylar ridge) to base of 2nd metacarpal
- function = wrist extension + abduction (with flexor carpi radialis)
- innervation = radial nerve (C6, C7 i.e. pre-division)
brevis = lateral epicondyle of humerus to base of 3rd metacarpal
- function = wrist extension + abduction (again with flexor)
- innervation = radial nerve (C7, C8 posterior interosseous)
24
Q
muscles innervated by radial nerve before it divides?
A
triceps brachii, anconeus, brachioradialis and extensor carpi radialis longus
25
extensor carpi ulnaris attachments?
function?
Innervation?
attachments = Lateral epicondyle of humerus to base of 5thmetacarpal
## Footnote
function = wrist extension and adduction (with flexor carpi ulnaris)
innervation = **radial nerve (C7, C8 posterior interosseous)**
26
extensor digitorum attachments?
Function?
Innervation?
tendons held against distal forearm by?
attachments = lateral epicondyle of humerus to dorsal expansion of digits 2-5 (NOT thumb)
Function = extension of wrist, extension of MCP (mostly) but also PIP + DIP of digits 2-5
innervation = **radial nerve (C7, C8 _posterior interoesseous_)**
The tendons of extensor digitorum are held against the distal forearm by the extensor retinaculum
27
Extensor digiti minimi attachments?
Function?
Innervation?
attachments = lateral epicondyle of the humerus to dorsal expansion of 5thdigit (little finger)
Function = extension of wrist + MCP, PIP, DIP of little finger
Innervation = **radial nerve (C7, C8 _posterior interosseous_)**
Having an extra extensor for this finger may help to support the medial side of the hand against a surface when performing precision movements with the thumb and index finger – for example to stabilise the hand when writing
28
extensor indicis attachments?
function?
innervation?
(part of deeper layer so no more space on lat. epicondyle)
Attachments = posterior surface of ulna (and interosseous membrane) to dorsal expansion of digit 2 (index finger)
Function = extension of wrist, MCP, PIP, DIP of index finger
innervation = **radial nerve (C7, C8 _posterior interosseous_**)
29
extensor pollicis longus attachments?
function?
Innervation?
attachments = ulna and interosseous membrane to base of distal phalanx of thumb
## Footnote
Function = extension of wrist + CMC, MCP and IP of thumb
Innervation = **radial nerve (C7, C8 _posterior interossoeus_)**
30
extensor pollicis brevis attachments?
function?
innervation?
attachments = radius and interosseousmembrane to base of proximal phalanx of thumb
## Footnote
function = extension of wrist and CMC + MCP of thumb joint
Innervation = **radial nerve (C7, C8, _posterior interosseous_)**
31
extensor pollicis brevis and longus contribute to?
borders of the anatomical snuffbox
32
Abductor pollicis longus attachments?
function?
Innervation?
Attachments = radius, interosseous membrane and ulna to base of 1st metacarpal
Function = abducts thumb + extends it at CMC, extends wrist
Innervation = **radial nerve (C7, C8 _posterior interosseous_)**
(This is away from the plane of the palm. If you lie the dorsum of your hand on a flat surface (for example a desk) and then move your thumb upwards away from the desk – this is abduction of the thumb)
33
Supinator attachments?
Function?
Innervation?
is it the most powerful supinator?
Nerve damage?
The deepest muscle in the posterior compartment
Attachments = crest of ulna, lateral epicondyle of humerus, radial collateral and annular ligament of radius to → lateral radius (proximal third)
Function = supination of forearm (rotates radius)
Innervation = radial nerve (deep/posterior interosseous)(C7,C8)
No - biceps brachii is the most powerful muscle for supination but supinator can also rotate the radius to supinate the forearm
biceps brachii is innervated by the musculocutaneous nerve, supinator is innervated by the radial nerve
so some supination can still occur if the musculocutaneous nerve is damaged
34
where does radial nerve pass between?
radial nerve passes between the lamina of supinator
35
what does radial nerve divide into?
Deep + superficial branch
Deep branch of the radial nerve = emerges from supinator to form the **posterior interosseous nerve** that runs with the posterior interosseous artery Superficial branch of the radial nerve = overlies part of brachioradialis before running through the roof of the anatomical snuffbox to supply skin on the dorsum of the hand
36
Radial artery formed from?
Superficial branch? How dos it enter the hand?
What does it form?
The radial artery is a terminal branch of the brachial artery
superficial branch of the radial nerve passes into the hand to supply sensory innervation to the lateral side of the dorsum of the hand
runs in the floor of the anatomical snuffbox and passes between the heads of adductor pollicis to enter the hand
It forms most of the deep palmar arch but will also anastomose with the ulnar artery as part of the deep and superficial arches
37
Muscles of posterior compartment of forearm supplied by?
Deep artery of the posterior compartment?
Most of the muscles of the posterior compartment are supplied by the deep interosseous branch of the radial nerve (except extensor carpi radialis longus)
Dep artery of the posterior compartment is the **posterior interosseous artery** which is a branch of the common interosseous artery which is derived from the **ulnar artery**
38
Why is the palm of the hand soft in comparison to the dorsum?
The palm of the hand has many small intrinsic muscles in addition to the long flexor tendons and so is relatively soft. The dorsum of the hand feels much harder and more bony as there are no muscles on the dorsum (the dorsal interossei lie between the bones)
39
what doe ssubcutaneous fat of dorsum of hand contain?
dorsum of hand tendons held in place by?
The dorsum has a layer of skin and subcutaneous fat that contains a dorsal venous arch and cutaneous nerves.
The other structures are the long extensor tendons that cross the dorsum of the wrist to reach the digits. The tendons are held to the wrist by an **extensor retinaculum** and each tendon is inside a small synovial sheath to protect it during movement of the tendon
40
what runs with the radial nerve in the hand?
boundaries?
The cephalic vein runs with the radial nerve (anatomical snuffbox at baseof thumb)
Boundaries of anatomical snuffbox:
* roof contains branches of the superficial branch of the radial nerve and the cephalic vein
* The floor is bony - formed from scaphoid, trapezium and base of 1st metacarpal
* medial and lateral borders are tendinous – medially the tendon of **extensor pollicis longus** (EPL on the diagram); and laterally the tendons of **extensor pollicis brevis (EPB) and abductor pollicis longus**
41
why is anatomical snuffbox of interest?
The snuffbox is an area of interest as the radial artery runs across the bones of the floor and can be palpated as a pulse point for the radial artery
42
what is the dorsal venous arch?
The dorsal venous arch is a communication between the cephalic vein (lateral side) and the basilic vein (medial side)
43
The slide shows the cephalic vein and radial nerve that lie superficially in the roof of the snuffbox and the radial artery that lies deep, between the tendons in the floor of the snuffbox
44
extensor and flexor retinalcula?
Extensor and flexor retincula = fascia that holds down tendons
45
What is the dorsal expansion?
E.g.?
The dorsal expansion is formed from connective tissue that wraps around the digits - it allows lon fingers and short muscles of the hand (e.g. **lumbricals**) to act on all 3 finger jonts
The lumbrical muscles cross the anterior surface of the metacarpophalangeal joint so can flex that joint, but because their tendon joins the expansion that wraps around the dorsum of the finger, they can exert pull on the posterior surface of the proximal interphalangeal joint and can extend it
46
tendons that cross the dorsum of the wrist?
lateral to medial
* abductor pollicis longus + extensor policis brevis
* extensor capri radialis longus + brevis
* extensor pollicis longus
* extensor indicis and extensor digitorum
* extensor digiti minimi
* extensor carpi ulnaris
(The tendons that cross the wrist together e.g. extensor indicis and extensor digitorum, usually share a synovial sheath)
47
…
48
movements between carpal bones?
type of joint CMC?
MCP?
IP joints?
Only small gliding movements can occur between the carpal bones
CMC = synovial plane **except** CMC at base of thumb which is **synovial saddle joint** that allows opposition of the thumb
MCP = synovial **condyloid** joints which allow flexion, extension, abduction, adduction + circumduction
interphalangeal joints = **synovial hinge** (alow flexion + extension of fingers)
49
first structure immediately beneath skin of the palm?
what is this?
Function?
what is it tightened by?
The first structure immediately beneath the skin of the palm is the **palmar aponeurosis**
It is a tough connective tissue layer that adheres to the skin of the palm
Function = helps hold the skin of the palm in place during movement to prevent the skin from slipping and loss of grip + protects the delicate nerves and vessels of the palm
It is tightened by palmaris longus from the forearm
50
palmaris brevis attachments?
where is it found?
Function?
Innervation?
attachments = palmar aponeurosis and flexor retinaculum to → dermis
lies superficial to the muscles of the hypothenar eminence
function = tightens palmar aponeurosis to enhance grip
Innervation = **ulnar nerve (superficial C8, T1)**
i.e. the nerve that supplies most of the intrinsic muscles of the hand
51
deepest intrinsic muscles of the hand?
extrinsic vs intrinsic muscles of hand
innervation?
The deepest muscles are called ‘interossei’ as they lie between the metacarpal bones of the hand
Intrinsic muscles are entirely within the hand, extrinsic muscles enter the hand from the forearm
The thumb (lateral) side of the hand is dominated by the median nerve so many of the muscles on that side (but not all) are supplied by the median nerve
The ulnar nerve dominates the little finger (medial) side of the hand and also supplies all of the deepest intrinsic muscles (the interossei)
52
intrinsic muscles of thenar eminence?
attachments? function? innervation?
3 muscles - 2 superficial and 1 deep
Abductor pollicis brevis
* scaphoid + trapezium to → base of proximal phalanx of thumb
* function = carpometacarpal (CMC) joint **abduction**
* innervation = median nerve (recurrent C8,T1)
Flexor pollicis brevis
* flexor retinaculum, capitate, trapezium to → base proximal phalanx of thumb
* function = CMC joint **flexion**
* Innervation = Median (recurrent) and some texts also ulnar nerve (C8,T1)
Opponens pollicis
* trapezium to → first metacarpal
* Function = CMC joint **opposition**
* Innervation = median nerve (recurrent C8,T1)
53
order of muscles in thenar eminence?
flexion innervation? Abduction?
superificial = abductor pollicis brevis (lateral) + flexor pollicis brevis (medial)
deep = opponens pollicis
The long abductor and flexor muscles originate in the forearm. This means flexion of the thumb is dominated by the median nerve but abduction is both radial and median nerves
54
recurrent median nerve?
supplies muscles of thenar eminence
(Median nerve sends a branch that passes backwards towards the thenar eminence – hence the name of the recurrent branch of the median nerve that supplies these muscles)
55
The slide shows the muscles of the thenar eminence as seen in a Thielembalmed cadaver. The other structure that is clearly seen on all of these images is the ulnar artery passing over the carpal tunnel to arch across the palm
56
which intrinsic muscle of the thumb is not part of thenar eminence?
attachments?
Function?
Innervation?
adductor pollicis
attachments = transverse head from 3rd metacarpal, oblique head from capitate and 2nd and 3rd metacarpals to → base of proximal phalanx of thumb
Function = adduction of CMC joint of thumb, flexion of MCP joint of thumb
Innervation = **ulnar nerve (deep C8, T1) - NOT median nerve**
57
muscles of hypothenar eminence?
attachments? Function? Innervation?
Abductor digiti minimi
* pisiform bone to → base of 5thproximal phalanx + dorsal digital expansion
* Function = abduction and flexion MCP joint little finger
* Innervation = ulnar nerve (deep C8,T1)
Flexor digiti minimi
* hamate, flexor retinaculum to → base of 5thproximal phalanx
* Function = flex MCP joint of little finger
* Innervation = ulnar nerve (deep C8,T1)
Opponens digiti minimi
* hamate + flexor retinaculum to → 5thmetacarpal
* Function = weak opposition of little finger (synovial plane (not synovial saddle) joint it cant pull the base of the finger towards the palm to allow pulp-to-pulp opposition in the way that opponens pollicis can for the thumb)
* Innervation = ulnar nerve (deep C8,T1)
58
order of muscles in hypothenar eminence?
The abductor lies at the medial edge of the eminence and the flexor lies more laterally
59
hypothenar eminence
60
Lumbricals?
features?
Insertion?
4 small muscles from tendons of flexor digitorum profundus
## Footnote
1st (index) and 2nd (middle) = unipennate
3rd (ring) and 4th (little) usually bipennate
Insert into **dorsal digital expansion**
61
Function of lumbricals?
Innervation?
MCP joint flexion and interphalangeal (IP) joint extension for digits 2-4
## Footnote
1st + 2nd = **median nerve (digital C8, T1)**
3rd + 4th = **ulnar nerve (deep C8, T1)**
62
Palmar interossei found?
Attachments?
Function?
Innervation?
Between metacarpal bones
there are 3 palmar interossei:
* 1st - from 2nd metacarpal to → base of 2nd proximal phalanx + dorsal expansion
* 2nd - from 4th metacarpal to → base of 4th proximal phalynx + dorsal expansion
* 3rd - from 5th metacarpal to → base of 5th proximal phalynx + dorsal expansion
Function = adduction towards middle finger (hence why middle finger doesn't have interossei), also flex MCP + extend IP of index, ring + little finger
Innervation = **ulnar nerve (deep C8, T1)**
63
Dorsal interossei attachements?
Function?
Innervation?
Little finger?
There are 4 dorsal interossei
Originate from sides of 2 adjacent metacarpals (e.g. 1st dorsal interossei from 1st + 2nd metacarpals)
* 1st = inserts into 2nd proximal phalynx + dorsal digital expansion
* 2nd + 3rd = inserts into 3rd proximal phalynx + dorsal digital expanion
* 4th = inserts into 4th proximal phalynx + dorsal digital expansion
Function = abduction of digits, flexion of MCP + extension of IP
Innervation = **ulnar nerve (deep C8, T1)**
The little finger already has abductor digiti minimi in the hypothenar eminence so does not need a dorsal interosseous muscle
64
Easy way to remember movements of interossei?
interesting to note?
DAB + PAD
Dorsal abduct, palmar adduct
It is interesting to note that the first dorsal interosseous muscle occupies the same webspace between the thumb and index finger as adductor pollicis. Seen from the palmar surface it is adductor pollicis that is visible, seen from the dorsal surface it is the first dorsal interossei that is visible
65
Which arteries supply the hand?
Palmar arches?
Supply to fingers?
Variation?
Radial and ulnar arteries anastomose to supply the hand
## Footnote
Superficial arch = mostly ulnar (ulnar artery crosses wrist above carpal tunnel)
Deep arch = mostly radial (radial artery passes in floor of anatomical snuffbox)
Digital branches of fingers are on the lateral surfaces of each digit (prevents damage during flexion + extension)
The superficial arch can very between individuals and some people do not have a communication between the radial and ulnar arteries. The deep palmar arch is very small and little variation has been found for this structure
66
superficial and deep **palmar** arches
67
in addition to deep arch, what does radial artery also form?
Where does radial artery pass?
In addition to the deep arch the radial artery also forms the **princeps pollicis artery** – the largest artery to the thumb and usually also supplies a vessel to the index finger
Radial artery passes through the anatomical snuffbox (over scaphoid and trapezium) into hand, passes between heads of adductor pollicis to anastomose with ulnar artery
68
Synovial sheaths?
What do these create?
Around tendons at wrist, palm and into digits
## Footnote
Small anatomical spaces created by synovium - palmar, thenar spaces + lumbrical tunnel (important for tracking spread of infection across palm)
69
Median and ulnar nerves in the hand?
The median nerve dominates the thumb (lateral) side of the hand and the ulnar nerve dominates the little finger (medial) side of the hand. The median nerve supplies the muscles of the thenar eminence and the lumbricals to the index and middle fingers. The ulnar nerve supplies the muscles of the hypothenar eminence and the lumbricals to the ring and little fingers in addition to adductor pollicis and all of the dorsal and palmar interossei
70
Cutaneous nerve supply to the hand?
The median nerve
* innervates the skin of the lateral side of the palm, the palmar surface of the thumb and the lateral two and a half digits (index, middle and half of the ring finger)
* It also innervates the dorsum of these fingers and the thumb between the DIP + PIP joints
The ulnar nerve
* Innervates the skin of both the palmar and dorsal surfaces of the medial side of the palm and the medial one and a half fingers (the little finger and half of the ring finger)
The radial nerve
* supplies skin on the thenar eminence and the lateral side of the dorsum of the hand
71
Cutaneous supply to upper limb?
The musculocutaneous nerve is motor in the anterior compartment of the arm but terminates as the lateral cutaneous nerve of the forearm
The medial cutaneous nerves of the arm and forearm are direct branches of the medial cord of the brachial plexus
The axillary nerve supplies motor innervation to teres minor and deltoid but has a sensory component that supplies skin in the badge patch area – the superior lateral part of the arm
72
Dermatomes of upper limb anterior?
2 different maps
73
Dermatomes of upper limb posterior?
I don't think we have to learn this
74
Specific dermatomes to remember?
C5 – in the badge patch area (superior lateral shoulder) carried by the axillary nerve
C6 – the pad of the thumb (this is the part on the palmar surface used for pulp-to-pulp opposition)
C7 – the pad of the middle finger
C8 – the pad of the little finger
T1 – the medial side of the elbow (though this is more disputed than the others)
75
Many of the superficial muscles of the anterior, or flexor, compartment of the forearm originate from the medial epicondyle of the humerus – the common flexor origin. Photograph A shows the most superficial muscle – pronator teres as it forms the medial boundary of the cubital fossa. Photograph B shows the full extent of pronator teres as it crosses the forearm to insert into the radius. It has 2 heads which are related to the median nerve – shown later in this presentation. It acts to pronate the forearm and is innervated by the median nerve.
Photograph C shows palmaris longus. This muscle may be absent in some individuals and can be present bilaterally or unilaterally in others. It acts to tense the palmar aponeurosis to improve grip and is innervated by the median nerve.
76
Flexor carpi ulnarisand flexor carpi radialis also originate from the common flexor origin. They both pass over the anterior surface of the wrist and act to flex the wrist. Both muscles also contribute to abduction (flexor carpi radialis) and adduction (flexor carpi ulnaris) at the wrist joint. Flexor carpi radialis is shown in photograph A as it passes distally towards the wrist, it is innervated by the median nerve.
Flexor carpi ulnarisis shown in photograph B. It is innervated by the ulnar nerve, as the ulnar nerve and artery lie immediately deep to this muscle.
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The final muscle to attach to the common flexor origin is flexor digitorum superficialis, shown in photograph A. It passes through the carpal tunnel into the hand to insert into the middle phalanx of the fingers. It crosses the anterior surface of the wrist and the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints, so flexes those joints. It is innervated by the median nerve.
Photograph B shows flexor digitorum profundus, which as its name suggests lies deep to superficialis in the forearm. There is no space left on the medial epicondyle so it attaches to the ulna and interosseous membrane. It passes through the carpal tunnel into the hand to insert into the distal phalanx of the fingers. It crosses the anterior surface of the wrist and the metacarpophalangeal (MCP), proximal interphalangeal (PIP) and distal interphalangeal joints (DIP) so flexes those joints. It is innervated by the median nerve for the lateral two digits (index and middle fingers) and the ulnar nerve for the medial two digits (ring and little fingers). This is because the medial side of the muscle lies immediately deep to the ulnar nerve.
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The long flexor of the thumb – flexor pollicis longus is shown in photograph A. It attaches to the radius and interosseous membrane and inserts into the distal phalanx of the thumb. It crosses the anterior surface of the wrist, metacarpophalangeal and interphalangeal joints of the thumb, so flexes those joints. It is innervated by the median nerve.
Photograph B shows the final muscle of this compartment – pronator quadratus. It lies close to the wrist and passes between the ulna and radius to assist in pronation of the forearm. It is supplied by the median nerve.
The last three muscles (the lateral side of flexor digitorum profundus, flexor pollicis longus and pronator quadratus) are all supplied by the anterior interosseous branch of the median nerve that lies with the anterior interosseous artery on the anterior surface of the interosseous membrane between the radius and ulna.
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The ulnar artery forms at or near the cubital fossa as a terminal branch of the brachial artery (shown in photograph A). It forms an ulnar recurrent artery to help supply the elbow joint and also a common interosseous artery that divides to form an anterior and a posterior interosseous artery. The interosseous arteries supply blood to the structures of the anterior and posterior compartments of the forearm.
The main part of the ulnar artery then passes distally down the forearm with the ulnar nerve (shown in photograph B), it then passes over the carpal tunnel and into the hand where it forms much of the superficial palmar arch. The ulnar nerve is a branch of the medial cord of the brachial plexus, it passes posterior to the medial epicondyle of the humerus to enter the forearm. It passes down the forearm and supplies flexor carpi ulnarisand the medial side of flexor digitorum profundusbefore passing over the carpal tunnel to enter the hand where it will supply many of the intrinsic muscles.
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The median nerve passes through the cubital fossa and into the anterior compartment of the forearm (shown in photograph A). It passes between the heads of pronator teres and divides to form an anterior interosseous branch that lies on the interosseous membrane with the anterior interosseous artery. The anterior interosseous branch supplies the deeper muscles of the forearm (the lateral side of flexor digitorum profundus, flexor pollicis longus and pronator quadratus).
Photograph B shows the main median nerve that supplies the rest of the superficial muscles of the forearm (except flexor carpi ulnaris). It passes through the carpal tunnel and into the hand where it will supply intrinsic muscles in the thenar eminence and the two lateral lumbricals.
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The radial artery forms at or near the cubital fossa from the brachial artery (shown in photograph A). It passes along the lateral side of the anterior compartment of the forearm and becomes superficial near the wrist joint (shown in photograph B). It passes through the anatomical snuffbox to reach the hand. The radial artery will be described further in the posterior forearm and dorsum of the hand presentation.
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All of the photographs on this slide are orientated with the base of the hand at the top of the image. Photograph A shows the roof of the carpal tunnel – the flexor retinaculum. This image shows the ulnar artery and nerve passing over the retinaculum to enter the hand and the muscles of the thenar eminence at the base of the thumb attaching to the retinaculum.
Photograph B shows the same wrist with the retinaculum removed to reveal the inside of the carpal tunnel. The long flexor tendons and the median nerve can be seen passing through the carpal tunnel.
Photograph C shows the same wrist with all of the tendons reflected to show the capsule of the wrist joint (shown by the arrow) that overlies the distal ends of the radius and ulna and the carpal bones.
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This slide shows some of the superficial structures of the posterior forearm and dorsum of the hand.
Photograph A shows the cephalic vein as it runs from the dorsum of the hand, along the lateral side of the forearm towards the cubital fossa.
Photograph B shows the superficial branch of the radial nerve as it passes from beneath brachioradialis to bring cutaneous innervation to the lateral side of the dorsum of the hand.
Photograph C shows the extensor retinaculum that passes over the long extensor tendons as they cross the posterior surface of the wrist.
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Photograph A shows anconeuson the posterior surface of the elbow joint – it extends the elbow and is innervated by the radial nerve.
Photograph B shows brachioradialis on the lateral surface of the forearm, indicated by the red plastic strip which has been placed under the muscle belly of brachioradialis. It is unusual in that it is a flexor of the elbow joint but is innervated by the radial nerve – the nerve associated with the extensor compartments of the arm and forearm.
Photograph C shows the superficial branch of the radial nerve as it passes from beneath brachioradialis.
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Photograph A shows extensor carpi radialis longus and photograph B shows extensor carpi radialis brevis. They both act to extend the wrist and assist flexor carpi radialis to abduct the wrist.
Extensor carpi radialis longus lies superior to brevis and attaches to the supracondylar ridge, whereas brevis attaches to the lateral epicondyle (the common extensor origin for the more superficial extensor muscles of the posterior forearm). Extensor carpi radialis longus is also innervated by the radial nerve prior to its division into superficial and deep (posterior interosseous) branches, brevis is innervated by the posterior interosseous branch.
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Photograph A shows the extensor of the wrist that lies on the medial side – extensor carpi ulnaris. It extends the wrist and assists flexor carpi ulnariswith adduction of the wrist. It is innervated by the posterior interosseous branch of the radial nerve.
Photograph B shows extensor digitorum, it runs along the central part of the posterior compartment of the forearm and forms 4 tendons that cross the dorsum of the wrist. It extends all of the joints of the fingers and is innervated by the posterior interosseous branch of the radial nerve.
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This slide shows two muscles that wrap around the dorsal surface of the radius. Photograph A shows abductor pollicis longus and photograph B shows extensor pollicis brevis. They both act to move the thumb, abductor pollicis longus moves the thumb away from the plane of the palm and extensor pollicis brevis extends the proximal phalanx of the thumb (a movement in the same plane as the palm).
Both are innervated by the posterior interosseous nerve and both contribute to the lateral boundary of the anatomical snuffbox.
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This slide shows two of the deeper muscles of the posterior compartment.
Photograph A shows the long extensor of the thumb – extensor pollicis longus, that forms the medial boundary of the anatomical snuffbox. Photograph B shows extensor indicis that acts with extensor digitorum to extend the index finger. Mobility and control of the index finger and thumb are important for a fine precision grip. Both muscles are innervated by the posterior interosseous nerve.
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The final extensor muscle is shown in photograph A – extensor digitiminimi. It acts with extensor digitorum to extend the little finger.
Photograph B shows supinator muscle as it wraps around the radius. It is the deepest muscle in the posterior compartment and acts with biceps brachii to supinate the forearm.
Both extensor digitiminimiand supinator are innervated by the posterior interosseous nerve. Photograph C shows the radial nerve as it passes through the lamina of supinator and divides to form superficial and deep (posterior interosseous) branches.
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The radial artery is formed in the cubital fossa from the brachial artery (shown in photograph A) it runs along the lateral side of the anterior compartment of the forearm before passing through the anatomical snuffbox and into the hand. The posterior interosseous artery is a branch of the common interosseous artery which is formed from the ulnar artery.
Photograph B shows the posterior interosseous (deep) branch of the radial nerve as it emerges from supinator, it supplies the muscles of the posterior compartment via many small branches, some of which can be seen in this photograph.
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This slide shows the anatomical snuffbox. Photographs A and B show the structures that lie in the skin of the roof of the snuffbox – the cephalic vein (shown in A) and the superficial branch of the radial nerve (shown in B). Photograph C shows the radial artery as it runs through the snuffbox over the scaphoid, trapezium and base of the 1stmetacarpal that form the bony floor of the snuffbox. This photograph also shows the tendinous medial (extensor pollicis longus) and lateral (extensor pollicis brevis and abductor pollicis longus) boundaries of the snuffbox.
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Photograph A shows the anterior surface of the hand – the palmar surface with the skin removed and the superficial fascia still intact.
Photograph B shows the palm after removal of the superficial fascia – this reveals the palmar aponeurosis that aids in grip and protects the structures of the palm.
The palmar aponeurosis is tightened by palmaris longus (photograph B) and palmaris brevis (photograph C).
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The small group of muscles near the base of the thumb form the thenar eminence. These muscles act to move the thumb at the carpometacarpal joint. Photograph A shows the short abductor of the thumb - abductor pollicis brevis (shown by the red plastic strip placed under the muscle belly). Photograph B shows the short flexor of the thumb – flexor pollicis brevis. These two muscles lie superficial to the third muscle of the thenar eminence – opponenspollicis (shown in photograph C). All of these muscles are supplied by the recurrent branch of the median nerve, though flexor pollicis brevis may be supplied by the ulnar nerve in some individuals.
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This slide shows the muscles that lie at the base of the little finger – in the hypothenar eminence. They are the equivalent muscles to those in the thenar eminence but move the little finger instead of the thumb.
Photograph A shows abductor digitiminimiand photograph B shows flexor digitiminimi. These two muscles lie superficial to opponensdigitiminimi(shown in photograph C). Opponensdigitiminimicannot create full opposition of the little finger as the carpometacarpal joint associated with the little finger is a plane synovial joint, unlike the synovial saddle joint for the thumb.
All of the muscles of the hypothenar eminence are supplied by the ulnar nerve.
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The lumbrical muscles originate from the tendons of flexor digitorum profundusas they cross the palm, this is shown for the first lumbrical muscle in photograph A. The lumbricals are numbered one to four (shown in photograph B). Number one passes to the index finger, two passes to the middle finger, three passes to the ring finger and four passes to the little finger. They insert into the dorsal expansion of each finger so cross the anterior surface of the metacarpophalangeal joint and the posterior surfaces of the interphalangeal joints. They can flex the MCP joint and extend the IP joints. Lumbricals one and two are innervated by the median nerve and numbers three and four are innervated by the ulnar nerve.
The long flexor tendons pass into the fingers to attach to the phalanges of the fingers. Photograph C shows the tendon of flexor digitorum superficialis splitting to attach to the middle phalanx of the middle finger. The tendon of flexor digitorum profunduscan be seen passing to the distal phalanx of the same finger.
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Photograph A shows adductor pollicis, it has two heads –a transverse and an oblique head. It acts to adduct the carpometacarpal joint and flex the metacarpophalangeal joint of the thumb. It is innervated by the ulnar nerve.
Photograph B shows the palmar interossei. They are numbered one to three and act to adduct the index finger, the ring finger and the little finger respectively. They cross the anterior surface of the metacarpophalangeal joint and then join the dorsal expansion for these fingers to cross the posterior surface of the interphalangeal joints, in a similar fashion to the lumbrical muscles. This means they can also flex the MCP and extend the IP joints for these fingers. All of the palmar interossei are innervated by the ulnar nerve.
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Photograph A shows the first dorsal interosseous muscle. The dorsal interossei act to abduct the fingers (spreading the fingers apart). They are numbered one to four (shown in photograph B). Number one passes to the index finger, numbers two and three to the middle finger and number four to the ring finger. The little finger already has abductor digitiminimiin the hypothenar eminence so does not need a dorsal interossei muscle.
The thumb also has its own abductor and adductor muscles so does not require any interossei muscles. Abduction and adduction move the digits away from or towards the middle finger. This means the middle finger does not move in adduction so does not have a palmar interosseous muscle but has two dorsal interossei to move it medially and laterally during abduction of the digits. All of the dorsal interossei are innervated by the ulnar nerve.
The first dorsal interosseous muscle occupies the dorsal part of the first web space so may be mistaken for adductor pollicis which occupies the palmar side of the same space.
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The hand is supplied by the radial and ulnar arteries. They anastomose with each through the palmar arches. Photograph A shows the superficial palmar arch which is formed mainly by the ulnar artery. Photograph B is a closer view of the superficial arch and shows the branches of the arch passing across the metacarpals towards the digits. It also shows the communication with the radial artery.
Photograph C shows the deep palmar arch which is mainly formed by the radial artery but is also joined by a deep branch of the ulnar artery.
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The motor supply to the muscles of the palm is from the median and ulnar nerves. These nerves also supply cutaneous innervation to the skin of the palm and the fingers. Photograph A shows the sensory branches of the median nerve. It supplies the palmar surface of the thumb, index finger, middle finger and lateral half of the ring finger. Photograph B shows the digital branches of the median nerve to the middle finger (and also the digital arteries), note that the digital nerves and vessels lie on the lateral sides of the digits.
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Photograph A shows the cutaneous branches of the ulnar nerve. The ulnar nerve supplies innervation to both the dorsal and palmar surfaces of the medial side of the hand and to both sides of the little finger and the medial half of the ring finger. Photograph B shows the median nerve passing to the lateral side of the ring finger and the ulnar nerve to the medial side of the ring finger. This is the classic pattern of innervation, though variation between individuals does exist.
Photograph C shows the superficial branch of the radial nerve, this supplies cutaneous innervation to the thenar eminence and also along the dorsum of the index, middle and part of the ring finger up to between the distal and proximal phalanx, then the median nerve supplies the most distal parts of these fingers.
